Technical Field
The present system relates to the field of underwater diving and, more particularly, to safety devices used while diving.
Background Art
Underwater diving typically involves a diver breathing from a source of compressed gas. A typical scuba tank for a recreational driver holds gas (e.g., air) at a relatively high pressure (such as 3,000 pounds per square-inch (psi)). The tank is often held by a buoyancy control device (BCD), also referred to as a buoyancy compensator or stabilizer. During use, the BCD is strapped onto the back of a scuba diver.
In a typical single-hose, open-circuit, two-stage scuba system, a first regulator stage reduces the gas pressure in the tank to a low pressure of, for example, 120 to 150 psi. A hose typically supplies gas at the low pressure to a valve on the BCD. The valve allows a diver to inject gas from the tank into one or more bladders in the BCD or to release air from the BCD into the water. In this way, the diver can control her buoyancy, often striving for neutral buoyancy during a dive and positive buoyancy (i.e., a supernatant condition) while ascending toward, or swimming on, the water surface.
Gas at the low pressure is also supplied by a hose to a second stage of the regulator, which is held by a diver's mouth. The second stage of a demand-valve regulator delivers breathable gas (e.g., air) at approximately ambient pressure to the diver's mouth or full-face mask. The ambient pressure, of course, depends of the water depth of the diver.
Another example of underwater diving equipment includes “Snuba” (a combination of the words, snorkel and scuba), which allows underwater diving with air supplied from the water surface. Instead of coming from a tank strapped to a diver's back, air is supplied to the second stage of the regulator from long hose connected to a compressed air tank at the water surface, held by a flotation device.
Upon occasion, an underwater diver encounters difficulty and should promptly ascend toward the water surface and/or summon help. For example, nitrogen narcosis (also sometimes referred to as “the martini effect”) can arise from breathing nitrogen at an elevated pressure (i.e., at substantial depth). It can impair a diver's judgment, coordination, and ability to focus mentally.
If, through inattention or the effects of nitrogen narcosis, a diver breathing air descends too deeply in the water, the diver can suffer from oxygen poisoning (as a result of breathing oxygen at too high a partial pressure).
For deeper dives, a diver may use a “non-air” gas mixture. A commercial scuba diver going to depths of 300 or more feet may use, e.g., 10 different bottles, with different combinations of gasses being supplied to the diver at different depths. If the diver's computerized valve assembly malfunctions (e.g., sea water seeps into the computer housing and degrades the performance of the valve controller), the diver must be able promptly to adjust the tank valves manually, a sometimes difficult task.
Divers at remote dive locations may sometimes have their tanks filled locally, near the dive site. On such occasions, a compressor, powered by a gasoline engine, may be used to pump air into the dive tanks. If the compressor operator is not careful, exhaust gas from the gasoline engine, including carbon monoxide, may be pulled in by the air compressor and pumped into a tank. Carbon monoxide is colorless, tasteless, odorless, and toxic.
Decompression sickness (also known as the bends or Caisson Disease) can affect a diver who surfaces too quickly. Upon descending in the water, the pressure around the diver increases, causing nitrogen to be absorbed into her body tissue. To release the nitrogen slowly from her body, a diver generally should ascend slowly and sometimes carry out decompression, or safety, stops. This allows the nitrogen to seep out of the body tissue slowly. If a diver ascends too quickly, however, there can be a build-up of nitrogen bubbles in the diver's body, adversely affecting the diver. A diver who is injured or otherwise under stress may encounter difficulty in ascending at a proper rate or following a desirable dive profile (including safety stops).
Of course, a diver may, at any time, experience an adverse health issue, such as a stroke or heart attack, requiring prompt medical attention. A muscle cramp (such as a debilitating stomach cramp) can pose a risk to a diver.